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ABDOMINAL RADIOLOGY Table of Contents   
Year : 2000  |  Volume : 10  |  Issue : 4  |  Page : 237-243
Comparative evaluation of ultrasonography and CT in patients with abdominal trauma: A prospective study


Dept of Radiodiagnosis, AIIMS, New Delhi - 110 029, India

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   Abstract 

Objectives: To assess the relative role of US and CT in patients with abdominal trauma and to compare it with operative findings or clinical outcome and also to suggest guidelines for imaging and management protocols based on the above results. Materials and Methods: Thirty-three consecutive and positive patients of abdominal trauma were evaluated with both ultrasonography (US) and computed tomography (CT). Thirty-one of them had blunt abdominal trauma. One patient had penetrating injury and another patient had blast trauma. Injuries to different organs were staged using organ injury scaling (OIS) system. Hemoperitoneum as detected on US and CT was scored. The US and CT findings were compared and correlated with the operative findings or clinical follow-up in conservatively managed cases Results: Patients with large hemoperitoneum required surgery more often. Grading of organ injuries did not correlate with need for surgery except for splenic injuries. In 25 patients, either US or CT would have been sufficient for arriving at a management decision. In seven patients, CT altered the management decision that was arrived at on the basis of US. One patient required angiography for diagnosis and vascular intervention. Conclusions: CT is better than US for the diagnosis of abdominal trauma. However US can be used as a useful initial modality. It is important that in all patients where US indicated presence of abnormality, in suboptimal US studies and in US-negative studies in symptomatic patients, the studies be supplemented with CT. Truly normal US scans in asymptomatic patients may be highly reliable for excluding significant organ injuries and these patients may be followed up without CT scan or admission.

Keywords: Ultrasonography (US), Computed tomography (CT), abdomen trauma

How to cite this article:
Mallik K, Vashisht S, Thakur S, Srivastava D N. Comparative evaluation of ultrasonography and CT in patients with abdominal trauma: A prospective study. Indian J Radiol Imaging 2000;10:237-43

How to cite this URL:
Mallik K, Vashisht S, Thakur S, Srivastava D N. Comparative evaluation of ultrasonography and CT in patients with abdominal trauma: A prospective study. Indian J Radiol Imaging [serial online] 2000 [cited 2019 Sep 17];10:237-43. Available from: http://www.ijri.org/text.asp?2000/10/4/237/30569
Patients with abdominal trauma present a frequent diagnostic dilemma because of low accuracy of physical examination and clinical diagnosis [1]. CT as the sole modality enables evaluation of other associated injuries in addition to global evaluation of abdominal trauma in hemodynamically stable patients and is extensively used in North American centers as the initial modality of diagnosis [2]. US is a rapid, repeatable, readily accessible modality and it is useful even in unstable patients. It is the preferred initial modality in continental Europe and Japan [3]. Though there are numerous studies in the literature comparing either CT or US with surgical findings, there is only one study, which compares both CT and US with operative findings or clinical outcome of patients [4]. We evaluated 33 patients with abdominal trauma both, with CT and US and compared their findings either with operative findings or with the clinical outcome in conservatively managed patients. Based on these results, we have tried to suggest guidelines for imaging and management protocols.


   Materials and Methods Top


In a prospective study over a period of 22 months (from May 1996 to February 1998), thirty- three patient of abdominal trauma, who were stable enough to undergo both US and CT and who had at least one of these scans interpreted as positive, were included in the study. Whenever possible, US preceded CT and the time gap between the two studies was kept to the minimum to make the studies comparable. Both US and CT scans were performed in all 33 patients; diagnostic peritoneal tapping was not performed in any of them. Patients with normal US and CT scans and patients who did not either require admission or were discharged after a short uneventful observation period, without any further investigation were excluded from the study.

Intra abdominal fluid is at least 1000 ml when US score is 3 or more.

US scans were performed on one of three machines depending on availability: Sonoline SL-2 (Siemens, Erlangen, Germany), Ultramark-9 HDI (ATL, Bothell, Wash) or Acuson 128XP/10 (Mountain View, California) with a 3.5 Mhz sector or curvilinear probes. Particular attention was paid to detection of free fluid in the abdomen and pelvis, in addition to assessment of individual organs. The state of distension and the presence of intraluminal echoes were looked for while scanning the gall bladder and urinary bladder.

CT scans were performed on one of three CT units; Somatom DRH (Siemens, Islein, NJ), Somatom PLUS 4 (Siemens, Iselin, NJ) or PQ 2000 (Picker International, Cleveland, Ohio) depending on availability. Routine oral (or through nasogastric tube) contrast agents in the form of 1-2% diluted ionic iodinated contrast was given 30-40 minutes before the study. Oral contrast was not given in patients with repeated vomiting or when limited information was required before proceeding for prompt laparotomy. All patients received intravenous bolus of iodinated contrast agents. Wide incremental sections were generally obtained for the lower abdomen and pelvis. Delayed CT scans were also incorporated whenever there was suspicion of kidney or urinary tract injury. Follow up US or CT scans were obtained as dictated by the clinical course of the patients.

Twenty-one patients were managed conservatively and 12 patients underwent surgery. The US and CT films of all 33 patients were independently reviewed by three radiologists (ST, DS and SV) without the prior knowledge of clinical follow up or operative findings. In case of difference of opinion, consensus was reached by discussion and general agreement.

Hemoperitoneum detected on US was scored as described by Huang et al [5] [Table - 1]. Similarly hemoperitoneum on CT was graded as described by Federle and Jeffrey et al [6] [Table - 2]. Individual organ injuries were graded according to the OIS system [7]. US and CT findings were compared with operative findings in 12 patients and with clinical outcome and follow-up in 21 conservatively managed patients. The results were analysed with respect to hemoperitoneum quantification and OIS grades. The overall imaging findings were analysed for their role in guiding the therapeutic options, whether conservative or surgical.


   Results Top


In our study population of 33 patients, the ages ranged from 4 years to 45 years, the mean age being 21.9 years. Nine patients belonged to the pediatric age group of 12 years or less. Only four patients were 40 years or older. There were 27 male and six female patients.

Of the 31 patients with blunt trauma, road traffic accident was the commonest mode of injury and it was the cause of abdominal trauma in 20 patients. In eight patients, the injury was caused by fall from height. Three patients had blunt injuries from other miscellaneous causes. One patient presented with penetrating injury and another patient had blast injury in the form of combination of blunt and penetrating injuries.

In 27 patients, US preceded CT and in six patients CT was done prior to US. The interval between the two examinations was less then 4 hours in 29 patients.

Of the total of 33 patients, 12 underwent surgery. One patient with pelvic fracture had a non-therapeutic laparotomy as he had hemoperitoneum and retroperitoneal hematoma but no intra-abdominal injury. Twenty-one patients were conservatively managed without any complication. There were three deaths, one of which was related to postoperative complications. The other patients died of associated head injuries.

Hemoperitoneum was detected on US in 19 patients. CT demonstrated hemoperitoneum in all of them and also in two more patients in whom US failed to detect hemoperitoneum. However, the associated solid organ injury was correctly detected on US in both these patients and they were conservatively managed. One patient with penetrating injury developed tense ascites requiring therapeutic tapping. He was excluded for the purpose of diagnosis and quantification of hemoperitoneum.

Nineteen patients with hemoperitoneum on US were scored according to guidelines suggested by Huang et al [5]. These patients were divided into two groups; those scoring less than three points (nine patients) and those scoring three or more points (ten patients). In the former group two patients underwent surgery. However, only one of them would have actually required surgery as the other patient had a non-therapeutic laparotomy. This suggests an 11% probability of needing a laparotomy in the below '3' score group. In contrast six patients out of 10 required operative management with a US score 3 or more, i.e. a 60% probability of needing a laparotomy [Table - 3].

Twenty-one patients with hemoperitoneum on CT were divided into three groups according to the Federle and Jeffrey system [6] [Table - 2]. These were 'small' (eight patients), 'moderate' (ten patients) and 'large' (three patients) All eight patients with small fluid hemoperitoneum on CT were conservatively managed and all three patients with large hemoperitoneum required surgical exploration. In the moderate fluid group, five patients were managed conservatively and the other five patients were surgically explored (the only case of non-therapeutic laparotomy is included in this group). Thus the rate of therapeutic laparotomy in patients with moderate hemoperitoneum on CT was 40% [Table - 4].

Among the solid organ injuries, the spleen was the commonest organ involved. There were 13 splenic, nine renal, six hepatic and two pancreatic injuries. Two patients had bowel injuries. One patient had vascular injury and he developed a traumatic aorto-mesenteric-portal fistula. He underwent an angiogram and embolization for its management. Three patients had multi-organ injuries. Organ injuries were graded using the OIS guidelines [7]. In our study of 33 patients, 13 had mild splenic injuries (grade II or grade III) and only one of them underwent surgery (because of presence of severe renal injury). Five of the seven patients with severe (grade IV and V) [Figure - 1] injuries required surgery. CT correlated well with surgical findings in all six operated cases. To compare the accuracy of US, the US findings were compared with CT in 11 patents. Two patients were excluded from

CT in 11 patents. Two patients were excluded from calculations as in one, CT preceded US and the ultra sonologist was aware of the splenic injury and in another case, the spleen was not visualised on US due to overlying surgical emphysema. The sensitivity, specificity and accuracy of US detection of splenic injuries were 73%, 100% and 90% respectively when compared with CT. US had a positive predictive value of 100% and negative predictive value of 87%.

Nine patients had kidney injuries and all of them were unilateral [Figure - 2]. Six patients had grade III, two patients had grade IV and one patient had grade V injury [Figure - 3]. Only two of the eight patients with renal injury upto grade IV required surgery. The only patient with grade V injury was operated upon as expected. The sensitivity, specificity and accuracy of US detection of kidney injuries were 67%, 100% and 91% respectively when compared with CT in all nine patients. The positive predictive value was 100% and negative predictive value was 89%.

Six patients had liver injures. Three patients had grade III and remaining three patients had grade IV injures [Figure - 4]. All liver injuries were demonstrated on both US and CT and were managed conservatively. Similarly two patients had grade II pancreatic injuries and both US and CT demonstrated them. Both these patients were managed conservatively.

Of the total 33 patients in our study, 26 patients had solid organ injuries (liver, spleen, pancreas or kidneys). CT OIS grading in these patients showed that all four patients with grade II injuries were conservatively managed, while both patients with grade V injuries were operated. However, the majority i.e. 20 of these 26 patients had either grade III or grade IV injuries and these were either managed conservatively or operated depending on their assessment on an individual basis [Table - 5]. Hence, in the overall analysis of solid organ injuries, OIS grading in isolation did not appear to predict the management protocols in most patients.

All 33 patients had evidence of injury on CT and out of these, US was interpreted abnormal in 29 patients. In the remaining four patients US did not reveal any abnormality i.e. US was false negative. Two of these had grade II splenic injuries and another two had bowel injuries as detected on CT.

We observed similar findings on US and CT in 19 patients. CT detected additional findings in 13 patients and angiography in one. The management was changed in favour of surgery in seven patients on the basis of additional information on CT. US as a sole modality would have had led to inappropriate care in this group. In the remaining six patients, additional information provided by CT did not change the therapeutic options. Thus 25 patients would have had adequate care on the basis of US alone. Seven patients in whom the CT changed the management included two patients of multi-organ injury, two patients of bowel injury and one patient each of pancreatic injury, urinary bladder injury and a case of blast injury with paralytic ileus and multiple retroperitoneal splinters. Though US was positive in all, it did not give the total diagnosis, which was crucial in influencing the decision making or determining the extent of surgery required.


   Discussion Top


The challenge in the imaging of abdominal trauma is to accurately identify injuries that require early exploration and at the same time avoid unnecessary operative intervention in cases that can be managed conservatively.

In recent years CT and US have to a great extent replaced all other modalities of investigation. But both have their limitations. In spite of diagnostic superiority, availability of CT is still limited and it also requires stable patients. On the other hand, inability to consistently detect pancreatic, bowel and mesenteric injuries and inability to functionally assess the kidneys and frequent interference by gaseous distension and associated bone or soft tissue injuries are major limitations of US [8].

There are very few prospective studies comparing CT and US in the literature [4]. We believe, this is the second study in literature after Liu et al . [9], in which all patients were prospectively subjected to both US and CT and in which all cases were positive for abdominal injury.

US scoring of hemoperitoneum shows that patients with a score of less than '3' are more likely to receive conservative management (the only patient who was operated upon in this category was for intraperitoneal bladder rupture). In contrast scores of '3' or more will frequently need surgical management (60% required surgery). Our findings are comparable with the observations made by Huang et al [5], though it is important to note that even in our patients with a score of 3 or more, a sizeable group (four out of ten patients) could be managed conservatively. This fact validates frequent observations by previous workers that hemodynamic stability is a major consideration in the management decision-making [10]. Though several workers in the past have mentioned that detection of hemoperitoneum mandates expedient laparotomy [2],[11 ], we observed that only eight of our 21 patients with hemoperitoneum on CT required surgical exploration. This is in agreement with the present trend towards conservative management of most of the solid viscous injuries.

We also found good correlation of CT quantification of hemoperitoneum with management approach. All eight patients with small fluid were conservatively managed and similarly all three patients with large fluid required surgical exploration. Approximately half of the patients with moderate fluid were explored. Taylor et al also reported similar experience [12].

CT detected minimal fluid in the two patients in whom US was false-negative. In one of these patients, ultrasound was performed 60 hours after the CT and the small hemoperitoneum might have resolved by this time as a natural process. We did not miss any moderate or large fluid on US unlike the experience of some previous workers [13]. This attests to the presently held opinion that US is reasonably accurate for detection of hemoperitoneum which is a frequent pointer to the presence of abdominal injury.

The OIS is a relatively new system that is gaining recent acceptance in literature. Though its sole purpose is to establish uniformity in different studies and thereby facilitate easy comparison, we found that splenic injury upto grade III infrequently required surgery. Only one out of six in this category required splenectomy as a part of surgery for multi-organ injury. On the contrary, grade IV or higher grade splenic injuries required surgery more often (five out of seven patients).

We found no correlation between the grade of kidney injury with the management outcome. Although two cases of grade III kidney injuries required nephrectomies because of persistent hematuria and associated multi-organ injuries respectively, it is quite possible, that in the absence of significant hematuria or multi-organ injuries, isolated renal injury upto and including grade IV can be conservatively managed.

Overall likelihood of surgical management increases with higher OIS grading of solid organ injury however OIS grading in isolation appears inadequate for predicting management protocol.

The present study demonstrates the superiority of CT over US, when we observe that in as many as seven of our patients CT altered the choice of management or influenced the extent of surgery by virtue of its global imaging capability including functional renal assessment. However it can be argued that in 25 patients either CT or US alone would have been adequate. Even in the seven patients in whom CT altered the management, five had evidence of intra-abdominal injury on US. In the case of the two patients with false negatives they had sufficient clinical features to suggest bowel injury and prompt a CT examination.

Unfortunately we have no data or follow up on our US negative and asymptomatic patients who were sent off without an initial CT. However these patients were normal on clinical examination and they were instructed to report back immediately in case they developed any symptoms. We have not come across any such patient returning for CT or US.

We conclude that CT is the superior diagnostic modality in the diagnosis of abdominal trauma. US can be a valuable initial investigation, however, US can miss crucial injuries and may lead to inappropriate management in some patients. Hence it is imperative that all US positive cases should be followed by CT. Similarly CT must also be performed in symptomatic patients with negative US scans and in patients with suboptimal US scans. Although a higher US or CT scoring of hemoperitoneum increase the chances of surgical management, hemodynamic stability and accurate imaging diagnosis are the main determinants which dictate the type of management strategies.

It appears that asymptomatic patients with normal clinical examination and US scans can be followed up without CT scan or indoor admission, restricting CT for US positives, US negative symptomatics and unsatisfactory US examinations. However as the diagnostic yields in most reported studies are relatively low [14], large clinical trials are required to find out whether such protocols can be safely followed.

 
   References Top

1.Colucciello SA. Blunt abdominal trauma. Emerg Med Clin North Am 1993; 11: 107-123.   Back to cited text no. 1  [PUBMED]  
2.Boulanger BR, Brenneman FD, McLellan BA, et al . A prospective study of emergent abdominal sonography after blunt trauma. J Trauma 1995; 39: 325-330.   Back to cited text no. 2    
3.Bode JP, Niezen RA, van Vugt AB, et al . Abdominal ultrasound as a reliable indicator for conclusive laparotomy in blunt abdominal trauma. J Trauma 1993; 34: 27-31.   Back to cited text no. 3    
4.Sivit CJ, Kaufman RA. Commentary: sonography in the evaluation of children following blunt trauma: is it to be or not to be? Padiatr Radiol 1995; 25: 326-328.   Back to cited text no. 4  [PUBMED]  
5.Huang MS, Liu ML, Wu JK, et al . Ultrasonography for the evaluation of hemoperitoneum during resuscitation: a simple scoring system. J Trauma 1994; 36: 173-177.   Back to cited text no. 5    
6.Federle MP, Jeffery RB. Hemoperitoneum studied by computed tomography. Radiology 1983; 148: 187-192.   Back to cited text no. 6    
7.Moore EE, Cogbill TH, Malagoni MA, et al . Organ injury scaling. Surg Clin North Am 1995; 75: 293-303.   Back to cited text no. 7    
8.Luks FI, Lemire A, St.-Vil D, et al . Blunt abdominal trauma in children: the practical value of ultrasonography. J Trauma 1993; 34: 607-610.   Back to cited text no. 8    
9.Liu M, lee CH, P' eng FK. Prospective comparison of diagnostic peritoneal lavage, computed tomographic scanning and ultrasonography for the diagnosis of blunt abdominal trauma. J Trauma 1993; 35: 267-270.   Back to cited text no. 9    
10.Mirvis SE, Whitely No, Gens DR. Blunt splenic trauma in adults: CT - based classification and correlation with prognosis and treatment. Radiology 1989; 171: 33-39.   Back to cited text no. 10    
11.Hoffman R, Nerlich M, Muggia-sullam M, et al . Blunt abdominal trauma in cases of multiple trauma evaluated by ultrasonography: a prospective analysis of 291 patients. J Trauma 1992; 32: 452-458.   Back to cited text no. 11    
12.Taylor GA, Fallat ME, Potter BM, et al . The role of computed tomography in blunt abdominal trauma in children. J Trauma 1988; 28: 1660-1664.   Back to cited text no. 12    
13.Gruessner R, Mentges B, Duber C, et al . Sonography versus peritoneal lavage in blunt abdominal trauma. J Trauma 1989; 29: 242-244.   Back to cited text no. 13    
14.Chiu WC, Cushing BM, Rodriguez A, et al . Abdominal injuries without hemoperitoneum: a potential limitation of focussed abdominal sonography for trauma (FAST). J Trauma 1997; 42: 617-625.   Back to cited text no. 14    

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Correspondence Address:
Sushma Vashisht
Dept of Radiodiagnosis, AIIMS, New Delhi - 110 029
India
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Source of Support: None, Conflict of Interest: None


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    Figures

[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4]

    Tables

[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5]

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